Personally, the only reason I can think I'd take a picture of my child at the bank, is if I were opening up their official savings fund (we have a different one for each child, and we actually did take pictures of them at the bank holding their papers the day we opened them...). Sure, there are probably other reasons- but that seems the most obvious to me.
It's possible she counted on being able to drain the children's savings fund and found out that Soloman was the only adult account holder, or that they had to have both signatures. I think if she had to have both she would have found a way to forge his signature (am I the only wife who knows how to do my husband's signature?). Or maybe they both had to be there in person, but I've never had that happen with a shared account unless it was a high dollar CD or something.
Anyway, I think that is a plausible happening. It also connects the photos and tells her "we know you tried to drain accounts..."